F30 320d timing chain rattle on cold start - normal or should I worry?

Thats pretty common on the B47 actually. The chain tensioner takes a moment to build oil pressure on cold start. If it goes away within 30-60 seconds its usually fine.

But keep an eye on it. If it starts lasting longer or you hear it when warm, get it checked asap. The B47 is way better than the N47 for chain issues but its not immune.

I work on these daily. 130k km is getting up there for the B47. I'd recommend getting the chain checked with ISTA - you can see the chain elongation values. If its within spec youre fine, if its borderline I'd plan for a replacement.

Budget around 1500-2000 EUR for the job at an indie shop.

Thanks both. I'll get it scanned this weekend. Hopefully its just the tensioner being slow. The car runs perfectly otherwise, no loss of power or anything weird.

had the exact same thing on my 2015 320d. turned out to be nothing, just cold start rattle. 160k km now and still going strong. these B47s are solid engines if you keep up with oil changes